1. Field of the Invention
The present invention relates to a piezoelectric sounding body for a sound producer and an electronic apparatus using same, and more particularly to reducing the thickness of a piezoelectric sounding body and electronic device.
2. Description of the Related Art
Piezoelectric sounding bodies are broadly used as simple electroacoustic transducer means. Particularly in recent years, they are frequently used for speakers and the like, in the field of cellular phones and personal digital assistants. The piezoelectric sounding body is structured by bonding piezoelectric elements 504, 510 on the both surfaces of a diaphragm 502, as exemplified in FIG. 11. The piezoelectric element 504 is structured by forming electrode layers 508A, 508B on the both surfaces of a piezoelectric member 506. This is bonded by, say, a conductive adhesive on the surface of a diaphragm 502 made of metal or the like. The other piezoelectric element 510 is similarly structured by forming electrode layers 508C, 508D on the both surfaces of a piezoelectric member 506.
The electrode layers 508A, 508D are respectively led to the outside through conductive means such as lead wires 512A, 512B. The other electrode layers 508B, 508C are held equal in potential to the diaphragm 502 and led from the diaphragm 502 to the outside through a lead wire 512C. For example, JP-A-2003-47092 discloses a structure similar to the electrode lead structure like the above.
However, in the related art, the lead wires 512A 512C and solder 514A-514C are required to lead the electrodes to the outside. Of those, the lead wires 512A, 512B have solder connections that are provided respectively on the electrodes 508A, 508D over the surfaces of the piezoelectric elements 504, 510. This forms a factor to increase the thickness of the piezoelectric sounding body 500 itself. For example, provided that the diaphragm 502 has a thickness 30 μm, the piezoelectric elements 504, 510 each have a thickness 60 μm and the solder connections 514A, 514B with the lead wires 512A, 512B each have a height 160 μm, then the overall thickness of the piezoelectric sounding body 500 amounts to 470 μm. Of the thickness, the solder connections with the lead wires 512A, 512B have totally a thickness of 320 μm as required in leading the electrodes. This occupies nearly 70% of the overall thickness of the piezoelectric sounding body 500. Meanwhile, in the related art, the connections of the lead wires 512A, 512B at the upper and lower surfaces do not allow the lead wires 512A, 512B to be placed in close contact with the diaphragm 502. Thus, the reliability is possibly insufficient for the severity of piezo-driving over a long time. For this reason, such a useless thickness, if eliminated by an improved electrode lead structure, can conveniently promote to reduce the thickness of a piezoelectric sounding body and an electronic device using same.